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Microbio Exam 2 > Lecture 9 - Microbial Genetics > Flashcards

Lecture 9 - Microbial Genetics Flashcards

1
Q

4 different levels of genetic study

A

organism level
cell level
chromosome level
molecular level

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2
Q

the sum of all types of genes constituting an organism’s distinctive genetic makeup

A

genotypes

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3
Q

the expression of the genotype that creates certain structures or functions

A

phenotype

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4
Q

where is DNA found in microorganisms?

A

cells

  • eukaryote
  • prokaryote
  • viruses
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5
Q

basic unit of DNA is

A

nucleotide

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6
Q

each nucleotide is composed of: (3)

A
  • phosphate
  • deoxyribose sugar
  • nitrogenous base
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7
Q

two types of nitrogenous bases

A

purines and pyrimidines

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8
Q

adenine pairs with

A

thymine

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9
Q

guanine pairs with

A

cytosine

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10
Q

original parental DNA strand

A

template strand

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11
Q

DNA goes under what type of replication

A

semiconservative replication

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12
Q

where is the origin of replication for DNA?

A

short sequence rich in adenine and thymine bases that are held together by only two hydrogen bonds. (TATA box)

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13
Q

because the origin of replication is AT-rich, ——– energy is required to separate the two strands than would be required if the origin were rich in G and C.

A

less energy

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14
Q

unwind the DNA helix

A

topoisomerase

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15
Q

unzips the DNA heliz

A

helicases

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16
Q

DNA replication - figure 9.6

A
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17
Q

synthesizing an RNA primer

A

primase

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18
Q

adding bases to the new DNA chain; proofreading the chain for mistakes

A

DNA polymerases III

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19
Q

removing primer, closing gaps, repairing mismatches

A

DNA polymerase I

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20
Q

final binding of nicks in DNA during synthesis and repair

A

ligase

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21
Q

making single-stranded DNA breaks to relieve supercoiling at origin

A

topoisomerase I

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22
Q

making double stranded DNA breaks to remove supercoiling ahead of origin and separate replicated daughter DNA molecules

A

topoisomerase II and IV

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23
Q

figure 9.7

A
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24
Q

DNA is used to synthesize RNA

A

transcription

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25
Q

RNA used to produce proteins

A

translation

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26
Q

transcription figure 9.12

A
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27
Q

translation figure 9.15

A
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28
Q

Drugs that inhibit protein synthesis:

A

rifamycins

actionomycin D

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29
Q

Drugs that interfere with the ribosome:

A

Erythromycin
Spectinomycin
Chloramphenicol
Aminoglycosides

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30
Q
  • Found only in bacteria and archaea
  • Coordinated set of genes regulated as a single unit
  • Can be inducible or repressible
  • Categories determined by how transcription is affected by the environment surrounding the cell
A

operons

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31
Q
  • Catabolic operons; operons encoding enzymes that act in catabolism
  • Operon is turned on (induced) by the substrate(s) for which the structural genes encode
  • Enzymes needed to metabolize a nutrient are only present when that nutrient is present in the environment
A

inducible operons

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32
Q
  • Contain genes coding for anabolic enzymes

- Several genes in a series are turned off (repressed) by the product synthesized by the enzyme

A

repressible operons

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33
Q

3 features of the lac operon

A
  • regulator
  • control locus
  • structural locus
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34
Q

composed of the gene that codes for the repressor, a protein capable of repressing the operon

A

regulator

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35
Q

two parts of the control locus

A

promoter and operator

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36
Q

recognized by RNA polymerase

A

promoter

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37
Q

acts as an on/off switch for transcription

A

operator

38
Q

made up of three genes, each coding for a different enzyme needed to catabolize lactose

A

structural locus

39
Q

figure 19.8

A
40
Q

Lac Operon Regulates Genes Based on Lactose Availability

A

—-???

41
Q

usually in the on mode

A

repressible operons

42
Q

Will only be turned off when the nutrient is no longer required

A

repressible operons

43
Q

serves as a corepressor to block the action of the operon

A

excess nutrient

44
Q

figure 9.19

A
45
Q

what type of cells do not have operons

A

eukaryotic cells

46
Q

together these interact with the promoter

A

enhancer and mediator

47
Q
  • Regulate gene expression for thousands of bp away
  • Position independent
  • DNA between enhancer and promoter loops out so that enhancer proteins can interact with proteins bound to the promoter
A

enhancer

48
Q
  • Large complex of proteins that mediate interaction between enhancer binding proteins and general transcription factors at the promoter
A

mediator

49
Q

An event in which one bacterium donates DNA to another bacterium

A

recombination

50
Q

what is the end result of recombination

A

a strain different from both the donor and recipient strain

51
Q

extrachromosomal DNA adept at moving between cells

A

plasmids

52
Q

any organism that contains and expresses genes that originated in another organism

A

recombinant

53
Q

Any transfer of DNA that results in organisms acquiring new genes that did not come directly from parent organisms

A

horizontal gene transfer

54
Q

three types of horizontal gene transfer in bacteria

A

conjugation
transformation
transduction

55
Q
  • A mode of genetic exchange in which a plasmid or other genetic material is transferred from a donor to a recipient cell via a direct connection
  • Can occur in both gram-positive and gram-negative cells
A

conjugation

56
Q

figure 9.20

A
57
Q
  • Bear genes for resisting antibiotics or other drugs
  • Commonly shared among bacteria through conjugation
  • Can confer multiple resistance to antibiotics
  • R factors can also carry genetic codes for resistance to heavy metals, or synthesizing virulence factors
A

resistance plasmids or factors

58
Q

The acceptance by a bacterial cell of small fragments of soluble DNA from the surrounding environment

A

transformation

59
Q

cells that are capable of accepting genetic material through transformation

A

competent

60
Q

figure 9.22

A
61
Q
  • The process by which bacteriophage serve as a carrier of DNA from a donor cell to a recipient cell
  • Occurs in a broad spectrum of bacteria
  • The participating bacteria in a single transduction event must be the same species
A

transduction

62
Q
  • Random fragments of disintegrating host DNA are taken up by a phage during assembly
  • Any gene from the bacterium can be transmitted
A

generalized transduction

63
Q

figure 9.23

A
64
Q

Transposable Elements - shifting segments of the genome

A

TE exists as a small DNA piece in genome

TE can change location (jump)

TE can replicate itself

The TE could insert into a plasmid and be transferred to other bacteria

65
Q

The smallest TEs consist only of two tandem repeats

A

insertion elements

66
Q

A type of TE that can transcribe DNA into RNA and then back into DNA for insertion in a new location

A

retrotransposon

67
Q

Other TEs contain genes that code for

A

antibiotic or toxin production

68
Q

Effects of TEs in bacteria:

A
  • Changes in colony morphology, pigmentation, and antigenic characteristics
  • Replacement of damaged DNA
  • Intermicrobial transfer of drug resistance
69
Q

The E. coli tet operon was originally identified as a _____ that confers resistance to the antibiotic tetracycline.

A

transposon (Tn10)

70
Q

bind to the operator of the tetracycline-resistance operon – similar to how the lac operon works

A

TetR protein

71
Q
  • Have the ability to make their hosts pathogenic.
  • Contain multiple genes that are coordinated to create a new trait on the bacterium
  • Islands flanked by sequences that look like genes for TE enzymes
A

pathogenicity islands

72
Q

Any change to the nucleotide sequence in the genome

The driving force of evolution

A

mutation

73
Q

A microorganism that exhibits a natural, nonmutated characteristic
The trait present in the highest numbers in a population

A

wild type

74
Q

an organism that bears a mutation

A

mutant strain

75
Q

A random change in the DNA arising from errors in replication that occur randomly

A

spontaneous mutation

76
Q

result from exposure to known mutagens

A

induced mutations

77
Q

Small mutations that affect only a single base on a gene

Involve addition, deletion, or substitution of single bases

A

point mutations

78
Q

mutations that lead to cell dysfunction or death

A

lethal mutation

79
Q

produce neither adverse honor helpful changes

A

neutral mutation

80
Q

Any change in the code that leads to placement of a different amino acids

A

missense mutation

81
Q

Changes a normal codon into a stop codon that does not code for amino acid

A

nonsense mutation

82
Q

Alters a base, but does not change the amino acid and has no effect
The redundancy of the code assures that certain amino acids will not be altered by a change in the third base of the codon

A

silent mutation

83
Q

occurs when a gee that has undergone a mutation reverses to its original

A

back mutation

84
Q

Occurs when one or more bases are inserted into or deleted from a newly synthesized DNA strand

A

frameshift mutation

85
Q

This alters the reading frame of the mRNA
Nearly always result in a nonfunctional protein
Every amino acid after the mutation is different from what is coded for in the original DNA
Insertion of bases in multiples of three does not disturb the reading frame

A

frameshift mutation

86
Q

Repair of damage caused by ultraviolet radiation

A

photoreactivation

87
Q

Mutations are excised by a series of enzymes that remove the incorrect bases and add the correct ones

A

excision repair

88
Q

Repair of damage caused by ultraviolet radiation

A

photoreactivation

89
Q

Mutations are excised by a series of enzymes that remove the incorrect bases and add the correct ones

A

excision repair

90
Q
  • A repair system can locate mismatched bases that were missed during proofreading
  • The base must be replaced soon after the mismatch is made, or it will not be recognized by the repair enzymes
A

mismatch repair

91
Q

Commonly used to rapidly detect chemicals with carcinogenic potential

A

ames test

92
Q

not repaired, permanent and heritable

A

mutations

Microbio Exam 2 (7 decks)

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